Total internal reflection critical angle:examples & applications

What is total internal reflection and when does it occurs ?

When a ray of light travelling in denser medium enters into a rarer medium, it bends away from the normal. If the angle of incidence ‘i’ increases’ the angle of refraction ‘r’ also increases. For a particular value of the angle of incidence, the angle of refraction becomes 90°. The angle of incidence, that cause the refracted ray in the rarer medium to bend through 90° is called critical angle.

When the angle of incidence becomes larger than the critical angle, no refraction occurs. The entire light is reflected back into the denser medium. This is known as total internal reflection of light.It is shown in figure below:

Applications of total internal Reflection:

Totally Internal Reflecting Prism

Many optical instruments use right -angled prisms to reflect a beam of light through 90° or 180° (By total internal reflection) such as cameras, binoculars, periscope and telescope. One of the angles of right angled prism is 90°. When a ray of light strikes a face of prism perpendicular, it enters the prim without deviation and strikes the hypotenuse at an angle of 45°. Since the angle of incidence 45° is greater than critical angle of the glass which is 42°, the light is totally reflected by the prism through an angle of 90°. Two such prisms are used in periscope. The light is totally reflected by the prism by an angle of 180°. Two such prisms are used in binoculars.

Total internal reflection in Optical Fibre

Total internal reflection is used in fibre optics which has number of advantages in telecommunication field. Fiber optics consists of hair size threads of glass or plastic through which light can be travelled.

The inner part of the fibre optics is called core that carries the light and an outer concentric shell is called cladding. The core is made of glass or plastic or relatively high index of refraction. The cladding is made of glass or plastic, but of relatively low refractive index. Light entering from one end of the core strikes the core-cladding boundary at an angle of incidence greater than critical angle and is refracted back into the core. In this way light travels many kilometers with small loss of energy.

Light Pipe

Light pipe is the bundle of thousands of optical fibres bounded together. They are used to illuminate the inaccessible places by the doctors or engineers. For example, doctors view inside the human body. They can also be used to transmit images from one point to another.

Endoscope

An endoscope is a medical instrument used for exploratory diagnostics, and surgical purposes. An endoscope is used to explore the interior organs of the body. Due to its small size, it can be inserted through the mouth and thus eliminates the invasive surgery. The endoscope used to examine the stomach, bladder and throat are called Gastroscope, Cystoscope and Bronchoscope respectively. An endoscope uses two fibre-optic tubes through a pipe. A medical procedure using any type of endoscope is called endoscopy.The light shines on the organ of patient to be examined by entering through one of the fibre tubes of the endoscope. Then light is transmitted back to the physician’s viewing lens through the outer fibre tube by the internal reflection. Flexible endoscopes have a tiny camera attached to the end. Doctor can see the view recorded by the camera on a computer screen.

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introduction to physics

Physics is an important and fundamental part of the physical sciences, in addition to its other disciplines as chemistry, astronomy, geology, etc. Physics is an experimental science and Scientific method emphasizes the need for accurate measurement of the various measurable characteristics of different phenomena or man-made objects. This site emphasizes the need through the understanding and practice of measuring and recording techniques and skills. Currently, there are three main frontiers of fundamental science. First, the world extremely large, the universe itself, radio telescopes gathered information from the other side of the universe and have recently detected, such as radio waves, the `` big bang firelight`` probably started off It standing universe almost 20 billion years ago. Second, the world of small extremely, the particles such as electrons, protons, neutrons, mesons and others. The third border is the world of complex matter. It is also the world of `` middle sized`` things, from molecules at one end of the earth to the other. This is all fundamental physics, which is the heart of science.
But what it is physical? according to a definition, physics is the study of matter, energy and the relationship between them. The study of physics is the investigation of such things as the laws of motion, the structure of space and time, nature and types of forces that hold different Together materials, the interaction between the different particles, the interaction of electromagnetic radiation with matter and so on.
In the late 19th century many physicist started believing that everything about physics has been discovered. However, on the beginning the 20th century many new experimental facts revealed that the laws made by previous researchers need modifications. Other researches gave birth to many new disciplines in physics as the nuclear physics that deals with atomic nuclei, particle physics that deals with the elementary particles that make up matter, relativistic mechanics that refers to speeds close to the light and the physics of solid state which is concerned with the structure and properties of solids, but this is not exhaustive.
Physics is the most fundamental of all sciences and other branches of science provides the basic principles and fundamental laws. This overlap of physics and other fields gave birth to new branches as physical chemistry, biophysics, astrophysics, physical health, etc. but also it plays an important role in the development of technology and engineering role.
Science and technology are a powerful force for change in the prospects of manking. The media and the media have brought rapid communications around the world in close contact with each other. Events in one part of the world immediately affect around the globe. We are living in the age of information technolgy. Computer networks are products developed chips from the basic ideas of physics. The chips are made from silicon. Silicon can be obtained from sand. It is up to cope make a sandcastle or computer out of it. So these were all fields and information physcis. And we are trying these all on this website